Xenasma guttulata S. Y. He, H. M. Zhou & C. L. Zhao 2025, sp. nov.

Xenasma guttulata S. Y. He, H. M. Zhou & C. L. Zhao sp. nov. Figs 10, 11 Diagnosis. Xenasma guttulata differs from X. pruinosum by its membranaceous basidiomata with a white to cream hymenial surface and larger basidiospores (6–7 × 3–4 µm vs. 7–9 × 5.5–7.5 µm). Holotype. China • Yunnan Province, Zhaotong, Wumengshan National Nature Reserve, GPS coordinates 27°29'N, 103°55'E, evel. 1900 m asl., on a fallen angiosperm branch, leg. C. L. Zhao, 29 August 2023, CLZhao 32193 (SWFC). Etymology. Guttulata (Lat.) refers to the basidiospores with guttules in the holotype. Basidiomata. Basidiomes annual, resupinate, closely adnate, without odor or taste when fresh, up to 2.5 cm long, 1.5 cm wide, and 100 µm thick. Hymenial surface smooth, membranaceous, white (60) to cream (4 A 2 / 3) when dry; sterile margin indistinct. Hyphal structure. Monomitic, generative hyphae with clamp connections, thin-walled, occasionally branched, interwoven, with dense crystal, 3.3–3.5 µm diam, IKI –, CB –; tissues unchanged in KOH. Cystidia abundant, cystidia tubular with obtuse apex, 75–91.5 × 4–8.5 µm, with slightly thick walls in the basal part that appears frequently collapsed, often with an apical amorphous globule. Cystidioles absent. Basidia clavate to subcylindrical, thin-walled, with two sterigmata and a basal clamp connection, 18.5–24 × 7.5–11 µm; basidioles in shape similar to basidia, but slightly smaller. Spores. Basidiospores ellipsoid to narrowly ellipsoid, thick-walled, verrucose, with several guttules, IKI –, CB –, 7–9 × 5.5–7.5 µm, Lm = 8.05 µm, Wm = 6.52 µm, Q = 1.23 (n = 30 / 1). Notes. Based on the ITS analysis (Fig. 3), the new species Xenasma guttulata was clustered with X. pruinosum (Pat.) Donk. However, X. pruinosum can be distinguished from X. guttulata by its smaller basidiospores (6–7 × 3–4 µm vs. 7–9 × 5.5–7.5; Donk 1957; Bernicchia and Gorjón 2010).